/Engine/Source/Runtime/CoreUObject/Public/AssetRegistry/AssetData.h
Returns true iff the given Object, assumed to be an Asset, is a TopLevelAsset (not a subobject, its outer is aUPackage). Only TopLevelAssets can be PrimaryAssets in the AssetManager. A TopLevelAsset is not necessarily the main asset in a package; see IsUAsset.
static bool IsTopLevelAsset ( [UObject](API\Runtime\CoreUObject\UObject\UObject) * Object )